A body moves in a straight line,with initial

velocity and uniform acceleration.find how
far it travels in 12sec.,given that it travels
246m in the first 6 sec.,and 69m in the last
3sec.find the initial velocity.

Please show step

2 answers

s(t) = s0 + v0t + a/2 t^2

so,

s0 + 6v0 + 18a = 246
s0 + 9v0 + 81/2 a = 246+69

Solve for v0
6 V0 + 18 a = 246

V0 + 9 a = V1

3 V1 + 4.5 a = 69

subs ... 3 V0 + 27 a + 4.5 a = 69
... times 2 ... 6 V0 + 63 a = 138

subtract to eliminate V0
... 45 a = -108
... a = -2.4

substitute back to find V0